C. difficile exposure in infancy may lead to natural immunization in children

A prospective cohort study, published in Clinical Infectious Diseases, has discovered exposure to Clostridium difficile in infancy produces an immune response, which may protect against this gastrointestinal infection later in childhood.

From a total of 32 healthy infants, researchers collected serum at 9–12 months old, 50% of the infants were colonized with toxigenic C. difficile more than 1 month prior to serology measurements.

Using assay analysis researchers discovered that the antibodies produced from early exposure neutralized the toxins that cause C. difficile infection, and the infants that were exposed to the bacteria had significantly greater serum anti-toxin antibodies compared with the infants who were not exposed.

The results from this study suggest that natural immunization occurs, however, future studies are required to determine the level of protection against C. difficile infection later in life.

“We found an immune response in infants colonized with C. difficile, which might be beneficial as they get older, although we are still studying the extent and duration of this natural immunization,” commented lead author Larry Kociolek (Stanley Manne Children’s Research Institute; IL, USA). “We are optimistic because we know from previous studies that adults with anti-toxin antibodies have a lower risk for illness from C. difficile infection.”

Infections in children and adults are frequently caused by C. difficile, with symptoms including diarrhea that need to be treated with antibiotics. In more severe cases, the infection may cause inflammation of the colon, which requires surgery and can become fatal.

As approximately one-half of infants will not be exposed to C. difficile, and therefore, will not develop natural immunization, the results from this study could potentially be used to develop a vaccine for children vulnerable to the infection.

“Given our results, we suspect that young children who get sick from C. difficile were probably not exposed as infants and so did not develop immunity,” explained Kociolek. “In adolescents, immunity might be waning. If with more research we can show that this is true, then there might be a role for vaccinating susceptible children and teens against C. difficile.”

Vaccines against C. difficile are currently in clinical trials for adults, however, separate pediatric trials would be needed before the vaccines could be available for children and adolescents.